Injection molding of hollow articles

Abstract

A hollow article such as an active bolster for an automobile is formed of an injection molded panel having a ridge and furrow adjacent a panel perimeter and an injection molded sheet having a bonding section at a sheet outer periphery, wherein the bonding section is within the furrow. An injection molded bond is formed between the bonding section and furrow, wherein a compression area where the sheet overlies a region of the panel adjacent the furrow is configured to constrain the bond to the furrow. An associated process and system facilitates mold alignment, part alignment, material strength, design adaptability, efficient processing, reduced labor, increased production rates, reduced energy consumption per part, aesthetically pleasing surfaces, and reduces or eliminates the need for a separate welding operation.

What is claimed is: 
     
       1. An inflatable active bolster, comprising:
 an injection molded panel having a pair of ridges extending perpendicular to an exterior surface of the injection molded panel adjacent a panel perimeter, wherein the ridges define a furrow therebetween; 
 an injection molded bladder sheet having a bonding section at a sheet outer periphery and adjacent a first pleat formed in a pleated region of the bladder sheet adapted to unfold during an inflation of the bolster, wherein the bonding section extends into the furrow perpendicular to the exterior surface of the panel; and 
 an injection molded bond joining the bonding section to the pair of ridges within the furrow; 
 wherein, prior to the inflation, the first pleat is compressed against the panel adjacent a first one of the ridges outside the furrow so that the bladder sheet bears on the first ridge to constrain the bond from flowing past the first pleat during injection molding of the bond. 
 
     
     
       2. The bolster of  claim 1  wherein the active bolster is an active bolster assembly configured for mounting in an interior of a motor vehicle. 
     
     
       3. The bolster of  claim 2  wherein the panel is a vehicle trim panel and the sheet is a pleated bladder. 
     
     
       4. The bolster of  claim 3  further comprising a plurality of detachably affixed tabs extending from the panel through the bladder, wherein an injection molded anchor attaches the tabs to the sheet. 
     
     
       5. The bolster of  claim 1  wherein the sheet further comprises a flange extending outwardly at the bonding section periphery and wherein the flange forms an attachment surface for the injection molded bond. 
     
     
       6. The bolster of  claim 1  wherein the panel and sheet are formed substantially simultaneously in a single injection molding machine. 
     
     
       7. The bolster of  claim 1  wherein the panel and sheet are co-molded in a three-part formation mold, and wherein the panel remains in a first mold of the formation mold and the sheet remains in a second mold of the formation mold during the injection molding of the bond.